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 A188050 a(n) = A016755(n) - A001845(n). 1
 0, 20, 100, 280, 600, 1100, 1820, 2800, 4080, 5700, 7700, 10120, 13000, 16380, 20300, 24800, 29920, 35700, 42180, 49400, 57400, 66220, 75900, 86480, 98000, 110500, 124020, 138600, 154280, 171100, 189100, 208320, 228800, 250580, 273700 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A016755 are odd cubes and A001845 are centered octahedral numbers, so the sequence might be regarded as odd cubes without their octahedral content. A000330 are square pyramidal numbers. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA a(n) = (10/3)*n*(n + 1)*(2*n + 1). a(n) = 20 * A000330(n). G.f.: 20*x*(1+x)/(1-x)^4. - Klaus Brockhaus, Mar 20 2011 MAPLE (10/3)*n*(n+1)*(2*n+1) MATHEMATICA 10n(n+1)(2n+1)/3 LinearRecurrence[{4, -6, 4, -1}, {0, 20, 100, 280}, 40] (* Harvey P. Dale, Jul 18 2016 *) PROG (MAGMA) A016755:=func< n | (2*n+1)^3 >; A001845:=func< n | (2*n+1)*(2*n^2+2*n+3)/3 >; [ A016755(n)-A001845(n): n in [0..40] ]; // Klaus Brockhaus, Mar 20 2011 CROSSREFS Cf. A016755, A001845, A000330. Sequence in context: A128676 A039455 A294112 * A027986 A240437 A174078 Adjacent sequences:  A188047 A188048 A188049 * A188051 A188052 A188053 KEYWORD nonn,easy AUTHOR Damien Pras, Mar 19 2011 STATUS approved

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Last modified February 21 11:54 EST 2019. Contains 320372 sequences. (Running on oeis4.)